1. Field of the Invention
This invention relates to a sheet material feeding device for feeding sheets of material, such as single slips, cut sheets or the like, one by one to a recording apparatus.
2. Description of the Related Art
Usually, in this kind of sheet material feeding device, the top sheet of recording paper set within a hopper is fed to the side of a platen in a recording apparatus by a feed roller, and is once stopped in a somewhat curved state while contacting the platen. The platen is then rotated to move the sheet to a position at which printing is started.
The sheet is once stopped in a somewhat curved state while contacting the platen in order to prevent the sheet from being inserted in an inclined state when the platen is rotated. The sheet is made parallel to the platen utilizing the resistive force (stiffness) of the sheet against the bending force.
Such a technique is described, for example, in Japanese Patent Public Disclosure (Kokai) No. 60-204566 (1985).
In the sheet feeding device as described above, the sheet of recording paper is made parallel to the platen utilizing the stiffness of the sheet. The stiffness of the sheet changes, however, due to temperature, humidity and the like at the moment of use. Hence, the sheet is not always inserted in a state parallel to the platen, but there is the possibility that the sheet is inserted in an inclined state.
Furthermore, the force required to push the sheet to the side of the platen and feed roller so that the sheet is easily caught when the platen rotates also utilizes the stiffness of the sheet. However, since the stiffness of the sheet is not constant due to the same reasons as described above, the sheet is not always favorably caught.
In order to solve such problems, a technique has been disclosed in U.S. Pat. No. 4,025,187 in which, by providing a member for pressing a curved portion of a sheet, the front end of which contacts a registration roller in a direction to flatten the curved portion, the front end of the sheet is securely contacted with a nip member of the registration roller to remove the inclination of the front end of the sheet.
Furthermore, when a printing operation is performed after reversing the sheet, the sheet is reversed after it has been fed immediately before being discharged and is returned to a manual insertion port, because it is troublesome if the sheet returns to the side of the feed roller. This approach has the following disadvantage.
That is, in order to return the reversed sheet to the manual insertion port separated from sheets of the recording paper at the side of the feed roller, a skirt made of an elastic material, such as a film or the like, is provided on the path for the sheets. However, since the skirt is, for example, easily broken or bent, there is the possibility that the sheet is not securely returned to the manual insertion port.
Such a technique has been disclosed in U.S. Pat. No. 4,565,462 or in Japanese Patent Public Disclosure (Kokai) No. 61-148081 (1986).